Method of forming thermoresponsive polymers

ABSTRACT

A method of forming a thermoresponsive polymer. The method proceeds by mixing 2-(3-(4-methyl-6-oxo-1,6-dihydropyrimidin-2-yl)ureido)ethyl methacrylate and methacrylamide in the presence of a solvent form a monomer solution. An initiator is then added to the monomer solution to form a thermoresponsive polymer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a non-provisional application which claims thebenefit of and priority to U.S. Provisional Application Ser. No.62/368,390 filed Jul. 29, 2016, entitled “Method of FormingThermoresponsive Polymers,” which is hereby incorporated by reference inits entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

None.

FIELD OF THE INVENTION

This invention relates to a method of forming thermoresponsive polymers.

BACKGROUND OF THE INVENTION

Thermoresponsive polymers are polymers that exhibit a drastic anddiscontinuous change of the physical properties with temperature.Temperature is a stimulus that can be applied easily and reversibly incontrast to, for instance, chemical additives.

There exists a need for a method of forming thermoresponsive polymers.

BRIEF SUMMARY OF THE DISCLOSURE

A method of forming a thermoresponsive polymer in organic solvent. Themethod proceeds by mixing2-(3-(4-methyl-6-oxo-1,6-dihydropyrimidin-2-yl)ureido)ethyl methacrylate(MAUPy) and methacrylamide (MAAm) in the presence of an organic solventto form a monomer solution. An initiator is then added to the monomersolution to form a thermoresponsive polymer.

A method of forming a thermoresponsive polymer. The method proceeds bymixing from about 0.01 mol % to about 50 mol %2-(3-(4-methyl-6-oxo-1,6-dihydropyrimidin-2-yl)ureido)ethyl methacrylateand from about 50 mol % to about 99.99 mol % methacrylamide in thepresence of a dimethyl sulfoxide solvent, at a temperature greater than50° C. to form a monomer solution. An azobisisobutyronitrile can then beadded to the monomer solution, in a molar ratio of 1:5 to 1:10,000, toform a thermoresponsive polymer. Upon completion of reaction thethermoresponsive polymer can also be purified in a polar solvent.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention and benefitsthereof may be acquired by referring to the follow description taken inconjunction with the accompanying drawings in which:

FIG. 1 depicts the method of forming a thermoresponsive polymer.

DETAILED DESCRIPTION

Turning now to the detailed description of the preferred arrangement orarrangements of the present invention, it should be understood that theinventive features and concepts may be manifested in other arrangementsand that the scope of the invention is not limited to the embodimentsdescribed or illustrated. The scope of the invention is intended only tobe limited by the scope of the claims that follow.

A method of forming a thermoresponsive polymer or a water-solublethermoresponsive polymer is shown in FIG. 1. The method proceeds bymixing 2-(3-(4-methyl-6-oxo-1,6-dihydropyrimidin-2-yl)ureido)ethylmethacrylate and methacrylamide (MAAm) in the presence of solvent formto a monomer solution, which can then be optionally degassed (101). Aninitiator is then added to the monomer solution to form athermoresponsive polymer (103).

Upon completion of polymerization, the polymer exhibits thermoresponsivebehavior through hydrogen bonding. When bonded together the hydrogenbonding groups can be either bonded by complementary hydrogen bondinggroups, or could be self-complementary bonded.

Non-limiting examples of the organic solvent that can be used includedimethyl sulfoxide, dimethyl formamide, ethyl acetate, methanol,dioxane, tetrahydrofuran, acetone, methylene chloride, chloroform, andtoluene.

In another embodiment the initiator can be an addition-type initiator,such as radical initiators. Non-limiting examples of addition-typeinitiators that can be used include azo initiators,azobisisobutyronitriles, peroxides, persulfates and redox systems. Inone embodiment the initiator can also be a UV initiator. Non-limitingexamples of peroxide initiators include: persulfate salts, hydrogenperoxide, alkyl peroxide, alkyl peroxyesters, peroxydicarbonates,hydroperoxides and combinations thereof. Non-limiting examples of azoinitiators include: 4,4′-azobis(4-cyanovaleric acid),4,4′-azobis-(4-cyanopentanoic acid),2,2′-azobis(2-methylpropionamidine)dihydrochloride,2,2′-azobis[2-(2-imidazolin-2-yl)propane]dihydrochloride,2,2′-azobis[N-(2-carboxyethyl)-2-methylpropionamidine]tetrahydrate,2,2′-azobis[2-(2-imidazolin-2-yl)propane],2,2′-azobis[2-methyl-N-(2-hydroxyethyl)propionamide],2,2′-azobis-(2-amidinopropane) dihydrochloride,2,2′-azobis(N,N′-dimethylene isobutyramidine) dihydrochloride,2,2′-zobis(N,N′-dimethylene isobutyramidine),2,2′-azobis-(isobutyramide)dehydrate, 2,2′-azobis-(N-ethylamidinopropanehydrochloride), 2,2′-azobis-(N,N′-dimethyleneamidinopropanehydrochloride), 2,2′-azobis(2-propane-2-carboxylic acid),2,2′-azobis-(2-methyl-N-(2-hydroxyethyl))propionamide,2,2′-azobis-[2-methyl-N-(1,1-bis(hydroxymethyl)]propionamide,2,2′-azobis-[2-methyl-N-(1,1-bis(hydroxymethyl)-2-hydroxyethyl)]propionamideand combinations thereof.

In one embodiment azobisisobutyronitrile can be dissolved in the same ordifferent solvent in molar ratios of 1:5 to 1:10000 with respect to themolar concentration of the monomer solution to form the thermoresponsivepolymer. Examples of ranges in molar ratios from 1:5, 1:10, 1:25, 1:501:75, 1:100, 1:500, 1:1000, 1:1500, 1:2000, 1:2500, 1:3000, 1:3500,1:4000, 1:4500, 1:5000, 1:5500, 1:6000, 1:6500, 1:7000, 1:7500, 1:8000,1:8500, 1:9000, 1:9500, 1:10000 or any range in between the numbersgiven. This initiator solution is then mixed with the monomer solutionto initiate the polymerization.

In one embodiment the monomer solution is heated to a temperaturegreater than 30° C., 35° C., 40° C., 45° C., 50° C., 55° C., 60° C., 65°C., 70° C., 75° C., 80° C., 85° C., 90° C., 95° C., 100° C., 105° C.,110° C., 115° C., 120° C., 125° C., 130° C., 135° C., 140° C., 145° C.,150° C., 155° C., 160° C., 165° C., 170° C., 175° C., 180° C., 185° C.,190° C., 195° C., or even greater than 200° C. The heating of themonomer solution can occur either by directly heating the monomersolution, incorporating the monomer solution into another solution witha greater temperature than the monomer solution, or any other methodknown of heating the monomer solution.

In another embodiment the mixing of the monomer solution occurs at anelevated temperature. Examples of the temperature in which the monomersolution can be mixed in include temperature greater than 30° C., 35°C., 40° C., 45° C., 50° C., 55° C., 60° C., 65° C., 70° C., 75° C., 80°C., 85° C., 90° C., 95° C., 100° C., 105° C., 110° C., 115° C., 120° C.,125° C., 130° C., 135° C., 140° C., 145° C., 150° C., 155° C., 160° C.,165° C., 170° C., 175° C., 180° C., 185° C., 190° C., 195° C., or evengreater than 200° C. The mixing of the monomer solution at an elevatedtemperature can occur by heating one component of the monomer solution,heating multiple components of the monomer solution or any other knownmethod of mixing the monomer solution at an elevated temperature. Thetime of the mixing can be any time necessary to achieve a thoroughdistribution of the monomers,2-(3-(4-methyl-6-oxo-1,6-dihydropyrimidin-2-yl)ureido)ethyl methacrylateand methacrylamide, within the monomer solution. Additionally, thereaction time can be any time necessary for the reaction of monomers,2-(3-(4-methyl-6-oxo-1,6-dihydropyrimidin-2-yl)ureido)ethyl methacrylateand methacrylamide to take place.

In one embodiment the thermoresponsive polymer is purified in a polarsolvent, such as alcohol. Examples of type of polar solvents that can beused include ethanol, methanol, acetone, water, tetrahydrofuran, etherand ethyl acetate.

In one embodiment the ratio of2-(3-(4-methyl-6-oxo-1,6-dihydropyrimidin-2-yl)ureido)ethyl methacrylateto methacrylamide in solution A ranges in mols percentage from0.01:99.99, 0.05:99.5, 1:99, 2:98, 3:97, 4:96, 5:95, 6:94, 7:93, 8:92,9:91, 10:90, 11:89, 12:88, 13:87, 14:86, 15:85, 16:84, 17:83, 18:82,19:81, 20:80, 21:79, 22:78, 23:77, 24:76, 25:75, 26:74, 27:73, 28:72,29:71, 30:70, 31:69, 32:68, 33:67, 34:66, 35:65, 36:64, 37:63, 38:62,39:61, 40:60, 41:59, 42:58, 43:57, 44:56, 45:55, 46:54, 47:53, 48:52,49:51, 50:50 or any range in between the numbers given.

There are a variety of methods in which the thermoresponsive polymer canbe incorporated into the wastewater. In one method it is possible thatthe thermoresponsive polymer is directly added into the wastewater. Inanother method, the thermoresponsive polymer is dissolved in a chemicalsolution, which solubilizes the polymer, and then incorporated in thewastewater. In one example the chemical is Sodium Chloride (NaCl)solution. The amount of chemical added can be from about 0.0001 wt % toabout 30 wt %, or from any amount greater than about 0.0005 wt %, 0.001wt %, 0.005 wt %, 0.01 wt %, 0.05 wt %, 0.1 wt %, 0.5 wt %, 1 wt %, toany amount smaller than about 25 wt %, 20 wt %, 15 wt %, 10 wt %, oreven about 5 wt %. Examples of wastewater can be from refineries such asdesalter effluent, produced water from oil and gas production sites,from paper making facilities, from municipal water treatment facilitiesor any other facility that produces wastewater. Wastewater can bebroadly defined as any aqueous environment that has high inorganic saltscontent (broadly defined as greater than or equal to 100 ppm, greaterthan or equal to 200 ppm or around 1000 ppm), suspended solids (≦500ppm), hydrocarbons (as free and/or emulsified oil), other organics andinorganics or combinations thereof.

In one embodiment, the average molecular weight of the thermoresponsivepolymer is greater than 50,000. In other embodiments, the averagemolecular weight is greater than 60,000, 62,000, 65,000, 70,000, 71,000,75,000 even greater than 80,000.

The following examples of certain embodiments of the invention aregiven. Each example is provided by way of explanation of the invention,one of many embodiments of the invention, and the following examplesshould not be read to limit, or define, the scope of the invention.

Example 1

The amounts of2-(3-(4-methyl-6-oxo-1,6-dihydropyrimidin-2-yl)ureido)ethyl methacrylate(MAUPy) and methacrylamide (MAAm) listed in Table 1, along with 1.2 mLof dimethyl sulfoxide solvent, were added to a 50 mL Schlenk flaskequipped with a stir bar. The chemicals started to dissolve afterimmersing the flask in a 70° C. oil bath under strong stirring. When thesolution was homogenous, the system was degassed by freeze-pump thawusing acetone-dry ice as a cold bath or by bubbling an inert gas. Afterdegassing, the solution was again immersed into the 70° C. oil bath topreserve the monomers in solution. In a separate small vial, thecorresponding amount of azobisisobutyronitrile (AIBN) was dissolved in100 μL of dimethyl sulfoxide solvent (DMSO), and subsequently degassed.The polymerization started after the addition of theazobisisobutyronitrile solution to the reaction flask at 70° C. under aninert atmosphere or by adding a radical inhibitor. These conditions weremaintained for 4 h. The polymerization was then quenched by exposing thereaction mixture to air at room temperature. Polymers were purified by24 h of stirring in methanol (100 mL) followed by 24 h of dialysis inmethanol (3000 g mol⁻¹ cut off).

TABLE 1 Sample MAAm ratio MAUPy amount MAAm amount AIBN amountPoly(MAUPy)-100  0 100 mg, 0.117 mg, 3.6 × 10−1 mmol 7.1 × 10−4 mmolPoly(MAUPy-MAAm)-70 30 100 mg, 13.01 mg, 0.17 mg, 3.6 × 10−1 mmol 0.15mmol 1.0 × 10−3 mmol Poly(MAUPy-MAAm)-50 50 100 mg, 30.37 mg, 0.23 mg,3.6 × 10−1 mmol 0.36 mmol 1.4 × 10−3 mmol Poly(MAUPy-MAAm)-20 80 100 mg,121.48 mg, 0.59 mg, 3.6 × 10−1 mmol 1.43 mmol 3.6 × 10−3 mmolPoly(MAUPy-MAAm)-10 90 100 mg, 273.32 mg, 1.17 mg, 3.6 × 10−1 mmol 3.24mmol 7.1 × 10−3 mmol Poly(MAUPy-MAAm)-5  95 100 mg, 577.01 mg, 2.34 mg,3.6 × 10−1 mmol 6.78 mmol 1.4 × 10−2 mmol Poly(MAUPy-MAAm)-2  98 100 mg,1.49 g, 5.86 mg, 3.6 × 10−1 mmol 17.49 mmol 3.6 × 10−2 mmol

Table 2 depicts the solubility of different samples of Poly(MAUPy-MAAm)

TABLE 2 Solubility Solubility in water MAAm in water at 175° F. withSample ratio 175° F. 1 wt % NaCl Poly(MAUPy-MAAm)-70 30 No YesPoly(MAUPy-MAAm)-50 50 No Yes Poly(MAUPy-MAAm)-20 80 No YesPoly(MAUPy-MAAm)-10 90 No Yes Poly(MAUPy-MAAm)-5  95 Yes YesPoly(MAUPy-MAAm)-2  98 Yes Yes

Example 2

Random copolymer of 5 mol % of2-(3-(4-methyl-6-oxo-1,6-dihydropyrimidin-2-yl)ureido)ethyl methacrylateand 95 mol % of methacrylamide were synthesized in DMSO and washed inwater (sample DMSO-DI). The apparent viscosity, specific viscosity andweight average molecular weight are shown in Table 3.

TABLE 3 Apparent Viscosity Specific Viscosity Polymer mPa-s (a.u.) Mw(g/mol)² DMSO-DI 1.074 ± 0.002 0.317 71,000 ± 1,000

In closing, it should be noted that the discussion of any reference isnot an admission that it is prior art to the present invention,especially any reference that may have a publication date after thepriority date of this application. At the same time, each and everyclaim below is hereby incorporated into this detailed description orspecification as an additional embodiment of the present invention.

Although the systems and processes described herein have been describedin detail, it should be understood that various changes, substitutions,and alterations can be made without departing from the spirit and scopeof the invention as defined by the following claims. Those skilled inthe art may be able to study the preferred embodiments and identifyother ways to practice the invention that are not exactly as describedherein. It is the intent of the inventors that variations andequivalents of the invention are within the scope of the claims whilethe description, abstract and drawings are not to be used to limit thescope of the invention. The invention is specifically intended to be asbroad as the claims below and their equivalents.

1. A method comprising: mixing2-(3-(4-methyl-6-oxo-1,6-dihydropyrimidin-2-yl)ureido)ethyl methacrylateand methacrylamide in the presence of an organic solvent to form amonomer solution; adding an initiator to the monomer solution to form athermoresponsive polymer.
 2. The method of claim 1, wherein the organicsolvent is selected from the group consisting of: dimethyl sulfoxide,dimethyl formamide, ethyl acetate, methanol, dioxane, tetrahydrofuran,acetone, methylene chloride and toluene and combinations thereof.
 3. Themethod of claim 1, wherein monomer solution is heated to a temperaturegreater than 50° C.
 4. The method of claim 1, wherein monomer solutionis heated to a temperature greater than 70° C.
 5. The method of claim 1,wherein the initiator is an addition-type initiator.
 6. The method ofclaim 1, wherein the initiator is selected from the group consisting of:azo initiators, azobisisobutyronitriles, peroxides, persulfates andcombinations thereof.
 7. The method of claim 1, wherein the mixing ofmonomer solution occurs at an elevated temperature.
 8. The method ofclaim 7, wherein the elevated temperature is greater than 50° C.
 9. Themethod of claim 1, wherein the thermoresponsive polymer is purified in apolar solvent.
 10. The method of claim 1, wherein the thermoresponsivepolymer is water soluble.
 12. The method of claim 1, wherein thethermoresponsive polymer has an average molecular weight greater than50,000.
 11. A method comprising: mixing from about 0.01 mol % to about50 mol % 2-(3-(4-methyl-6-oxo-1,6-dihydropyrimidin-2-yl)ureido)ethylmethacrylate and from about 50 mol % to about 99.99 mol % methacrylamidein the presence of a dimethyl sulfoxide solvent, at a temperaturegreater than 50° C., to form a monomer solution; addingazobisisobutyronitrile, in a molar ratio of 1:5 to 1:10,000, to themonomer solution to form a thermoresponsive polymer; and purifying thethermoresponsive polymer in a polar solvent.